For space missions to either the Moon or Mars, protecting mechanical moving parts
from the abrasive effects of prevailing surface dust is crucial. This paper compares
the abrasive effects of two lunar and two Martian simulant regoliths using special
pin-on-disc tests on a stainless steel/polytetrafluoroethylene (PTFE) sealing material
pair. Due to the regolith particles entering the contact zone, a three-body abrasion
mechanism took place. We found that friction coefficients stabilised between 0.2 and
0.4 for all simulants. Wear curves, surface roughness measurements, and microscopic
images all suggest a significantly lower abrasion effect of the Martian regoliths
than that of the lunar ones. It applies not only to steel surfaces but also to the
PTFE pins. The dominant abrasive micro-mechanism of the disc surface is micro-ploughing
in the case of all tests, while the transformation of the counterface is mixed. The
surface of pin material is plastically transformed through micro-ploughing, while
the material is removed through micro-cutting due to the slide over hard soil particles.
